class Person {}

function mixinRunner(BaseClass) {
  class newClass extends BaseClass {
    running() {
      console.log("running~");
    }
  }

  return newClass;
}

function mixinEater(BaseClass) {
  return class extends BaseClass {
    eating() {
      console.log("eating~");
    }
  };
}

class Student extends Person {}

var newStu = mixinEater(mixinRunner(Student));
var ns = new newStu();
ns.running();
ns.eating();
